A hot issue currently being debated in the courts involves the intersection of privacy law and technology: the ability to use cellular phone signals to track the location of users. As communications technology grows more powerful, it becomes easier to collect information on consumers that subscribe to services such as cell phone providers and GPS locators, which require constant interaction with towers or satellites. The government has seized upon the ability to track people using this electronic data in order to strengthen its investigatory practices. The argument for easy access to such information is that particularly in the age of increased awareness of and sensitivity to the potential for domestic terrorism, knowing the location of possible perpetrators is crucial to uncovering and shutting down criminal activity as quickly as possible. However, the high potential for abuse of the privacy rights of individuals that use these services is serious enough that the Department of Justice has been taken to court repeatedly in recent months, in order to determine just where the line between legitimate investigation and protection of privacy should be drawn.

The purpose of this article is to discuss recent cases that address the standard that courts have placed upon investigators to procure real-time tracking information from data communications companies.

For a cellular phone to readily receive calls there must be continuous communication between the physical phone and the service provider's satellite towers. This signal can be used by phone companies to track the whereabouts of individuals. Developing technology coupled with an increasing number of cell sites built to handle the rapidly expanding cell phone market have led to increased accuracy in triangulating the physical location of a user. A useful tool for locating 911 callers from their cell phones,1 the service can be used to track any individual with a cell phone that is powered on, regardless of whether or not the user is engaged in a call.

Law enforcement officials have long used data stored by cell phone service providers to track individuals suspected of committing crimes, but no statute clearly sets out the standard for what evidence is needed before court-ordered disclosure of this information may be granted. Recently a number of decisions have been passed down discussing cell phone tracking and the standard by which law enforcement officials may request data to locate an individual via their cell phone. Of the six decisions handed down (from the Eastern District of New York, Southern District of Texas, District of Maryland, Southern District of New York,

District Court for the District of Columbia and Eastern District of Wisconsin),2 four ruled that a search warrant based on probable cause is required before law enforcement can track someone's location using cell phone data.3 Although judges have urged the Department of Justice to appeal the rulings so that a uniform standard can bring clarity to the issue, the DOJ has declined to do so. The lone case rejecting probable cause as the required standard was handed down in December 2005 from the Southern District of New York.4

The issue raised in these cases is whether "real-time" cell site information that locates a user, regardless of whether or not they are engaged in a call, requires a different burden than requesting pen register information (a record of outgoing calls from a particular number) or trap and trace information (a record of incoming calls to a particular number). In the absence of legislation regarding cell site tracking information, the government has argued that a combination of two statutes provides the right to request such information at a standard lower than probable cause: the Stored Wire and Electronic Communicati